		window.onload=function(){

			//1rem=20px
			var oW=document.documentElement.clientWidth;

			document.documentElement.style.fontSize=oW/375*20+'px';

			//oW/16=1rem=?px
			//屏幕宽度/320 = 1;
			//屏幕宽度/20   /16 = 1 

			//屏幕宽度/320 = 屏幕宽度/20 /16
			//px
//---------------------------------------
			//屏幕宽度/320 = ?/20
			//oW/320=?/20
			//oW/320*20=?
		}

